Does your iPod sound nasty when you turn it up loud?

Not that I listen to my iPod loud, or usually at all for that matter.
(You shouldn't listen to yours loud either: it will damage your
hearing, which you will never get back once lost, and besides, extra
volume is almost always an unsatisfactory compensation for a lack of
fidelity somewhere in your system that you should seek, locate
and correct. But I digress...) My iPod is filled with uncompressed
music that I use as a (relatively) high-quality source when
prototyping and building amplifiers.

Today I needed to feed a preamp with a 1kHz
sine wave. I have an audio CD full of sine waves (and other torture
devices) so rather than build a cheesy little signal generator out of
an op-amp and a light bulb I thought I'd be ever-so-21st-century about
it and upload the CD to my iPod to turn it into a signal generator on
steroids. And lo...

This is what a 1kHz sine wave looks like, playing on my iPod with
its volume control set at one notch less than maximum:

Pretty, isn't it?

This sine wave is recorded at '0 dBFS' (which is geek speak for saying
that it is at, but not beyond, the maximum amplitude that
digital audio should correctly reproduce). When fed with a 0 dBFS
sine wave a well-behaved system produces exactly the waveform above,
and will do so regardless of where you set the volume control
(above zero). So far so good.

Here's the same 1kHz sine wave played with the iPod volume increased (by one
notch) to maximum:

The built-in amplifier in the iPod can't cope: the waveform is
horribly clipped, with the peaks and troughs severely flattened. This
might not have been disastrous fifteen years ago (when there was
still some dynamic range left in many recordings) but these days, with
the loudness wars keeping most recordings at 0 dBFS as much as humanly
possible, if you listen to your iPod turned all the way up then this
is going to cause noticeable distortion (of the nastiest
kind) on a lot of material.

When I did listen to my iPod a lot I almost always used an external
headphone amplifier (to take the strain off the built-in amplifier
with low-impedance headphones, or to get a reasonable level with
high-impedance ones). The headphone amp had a volume control of its
own that I used while leaving the iPod's volume alone. I never liked
the sound with the iPod turned up full and now I know why: Apple
designed the iPod's volume control to go all the way to '11', even
though they probably knew that '10' was the limit.

(I get the same result regardless of load and regardless of power
source, battery or charger. The so-called 'EQ' setting is off. The
iPod in question is a 4G.)